Consolidated Statements of Stockholders' Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock Issued [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance, Stockholders' Equity at Dec. 31, 2009	$ 330.2	$ 0.1	$ 216.2	$ (13.2)	$ 129.6	$ (2.5)
Beginning Balance, Shares, Issued at Dec. 31, 2009		11.0		(0.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17.7				17.7
Other comprehensive (loss) income, net of tax	1.4					1.4
Stock-based compensation expense	4.8		4.8
Cash proceeds from exercise of common stock options and warrants, shares		0.5
Cash proceeds from exercise of common stock options and warrants, value	8.3		8.3
Excess tax deductions associated with stock-based compensation	2.0		2.0
Issuance of stock based instruments, net of shares withheld for employee taxes, shares		0.1
Issuance of stock based instruments, net of shares withheld for employee taxes, value	(1.7)		(1.7)
Ending Balance, Stockholders' Equity at Dec. 31, 2010	362.7	0.1	229.6	(13.2)	147.3	(1.1)
Ending Balance, Shares, Issued at Dec. 31, 2010		11.6		(0.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	26.2				26.2
Other comprehensive (loss) income, net of tax	(3.0)					(3.0)
Dividend declared	(1.9)				(1.9)
Stock-based compensation expense	5.1		5.1
Cash proceeds from exercise of common stock options and warrants, shares		0.7
Cash proceeds from exercise of common stock options and warrants, value	5.4		5.4
Excess tax deductions associated with stock-based compensation	1.7		1.7
Issuance of stock based instruments, net of shares withheld for employee taxes, shares		0.1
Issuance of stock based instruments, net of shares withheld for employee taxes, value	(1.7)		(1.7)
Repurchase of common stock, shares				(0.5)
Repurchase of common stock, value	(19.0)			(19.0)
Ending Balance, Stockholders' Equity at Dec. 31, 2011	375.5	0.1	240.1	(32.2)	171.6	(4.1)
Ending Balance, Shares, Issued at Dec. 31, 2011		12.4		(1.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	33.9				33.9
Other comprehensive (loss) income, net of tax	(2.5)					(2.5)
Dividend declared	(10.6)				(10.6)
Stock-based compensation expense	6.2		6.2
Cash proceeds from exercise of common stock options and warrants, shares		0.1
Cash proceeds from exercise of common stock options and warrants, value	3.8		3.8
Excess tax deductions associated with stock-based compensation	1.1		1.1
Issuance of stock based instruments, net of shares withheld for employee taxes, shares		0.1
Issuance of stock based instruments, net of shares withheld for employee taxes, value	(2.0)		(2.0)
Repurchase of common stock, shares				(0.1)
Repurchase of common stock, value	(5.2)			(5.2)
Ending Balance, Stockholders' Equity at Dec. 31, 2012	$ 400.2	$ 0.1	$ 249.2	$ (37.4)	$ 194.9	$ (6.6)
Ending Balance, Shares, Issued at Dec. 31, 2012		12.6		(1.1)